Ink jet type recording heads include a nozzle substrate, an ink chamber substrate, a vibration plate, and a piezoelectric element bonded to the vibration plate. A pressure chamber to which ink is introduced is formed in the ink chamber substrate, and the vibration plate is in contact with the pressure chamber. The piezoelectric element is formed by laminating a lower electrode, a piezoelectric layer, and an upper electrode on the vibration plate.
In some ink jet type recording heads , the lower electrode, the piezoelectric layer, and the upper layer constituting the piezoelectric element are provided in a region facing the pressure chamber with the vibration plate interposed therebetween, so that they are formed to have the same pattern and have the same shape and size.
A piezoelectric material used to form the piezoelectric layer is, for example, a metal oxide represented by PZT (PbZrxTi1−xO3). Such a piezoelectric material is formed of sintered compounds of crystal grains, and in performing etching to pattern the piezoelectric layer, the piezoelectric layer is cut up by the crystal grains or the material constituting the piezoelectric layer is being removed as the crystal grains are attached. For this reason, an end surface of the piezoelectric layer after patterning is performed has depressions and protrusions, rather than a smooth surface. Therefore, when a driving voltage (e.g., 30V to 40V) is applied between the upper electrode and the lower electrode disposed with the piezoelectric layer interposed therebetween, sparks are generated to cause a short-circuit between the upper electrode and the lower electrode. In particular, when the piezoelectric layer is formed as an extremely thin layer having a thickness of about 2 μm, the spark problem between the upper electrode and the lower electrode becomes particularly noticeable.